#10004: The gap instances in a parallelised function do not always have distinct
_local_tmpfile
--------------------------+-------------------------------------------------
Reporter: SimonKing | Owner: was
Type: defect | Status: needs_review
Priority: blocker | Milestone: sage-4.6.1
Component: interfaces | Keywords: _local_tmpfile, parallel
Author: Simon King | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
--------------------------+-------------------------------------------------
Changes (by newvalueoldvalue):
* status: new => needs_review
* author: => Simon King
Comment:
Now it seems to work! With the patch, I get
1. Caching works
{{{
sage: gap._local_tmpfile() is gap._local_tmpfile()
True
}}}
2. Different interfaces have different tmpfiles:
{{{
sage: gap._local_tmpfile() != singular._local_tmpfile()
True
}}}
3. Parallelisation works:
{{{
sage: @parallel
....: def f(n):
....: return gap._local_tmpfile()
....:
sage: L = [t[1] for t in f(range(5))]
sage: len(set(L))
5
sage: print gap._local_tmpfile()
/home/king/.sage//temp/gauss/24281//interface//tmp24283
sage: L = [t[1] for t in f(range(5))]
sage: len(set(L))
5
}}}
The ideas for my patch are:
1. As before, the name of the file is cached in an attribute
!__local_tmpfile.
2. If !__local_tmpfile is not there or is None, then a new filename is
created, which depends on pid(). This is different for different interface
instances, including different forks of a parallelised function.
3. It must be ensured that the cache is emptied before forking. This is
implemented in {{{Expect.quit()}}}: !__local_tmpfile is set to None (I
tested that !__delattr!__ did not do the job).
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10004#comment:4>
Sage <http://www.sagemath.org>
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